It's where the snowcapped Andes Mountains tumble spectacularly into the sea. Where rivers roar with glacial waters. Where 3,000-year-old Alerce trees strain for the sky. Where sea lions rule from their perch on the rocky coast.

And where an American millionaire has bought every acre the eye can see. His mission: preserve this magnificent landscape forever. And as much wilderness as his money can buy.

Our story begins with the journey to find him. Getting to Pumalin from the United States takes more than two days. Flights; a dusty highway; a ferry ride; more highway; then a five-hour boat ride down a majestic fjord. You really have to want to get there.

The final leg: an early morning boat ride to the end of another fjord. And then it gets really interesting. The boat beaches on mud flats, a tractor with giant wheels spins toward us from the trees. Wondering just where we are being taken, the "Nightline" crew piles into the back with its gear.

Paradise Found

Suddenly, in this remote mountain valley near the bottom of the earth, we enter a manicured lane way, passing immaculate gardens, glass greenhouses and then, far from everyone and everywhere, a graceful home. This is where Doug Tompkins and his wife, Kristine, live.

Their passion: saving this Earth. And with their millions of dollars, they have the means to do something about it.

You can hear the anger in Doug's voice when the subject turns to the environment.

"As we see this human project sweeping across the globe, wiping out everything in its trajectory, it's upsetting," Doug said. "I don't want to call it anger, but it's upsetting and I try to use my 'upsetedness,' if you will, to get me going in the morning. We are immersed in a serious crisis, and we have to rethink the living arrangements on the planet."

And so the Tompkinses have single-handedly decided to devote their wealth to preserving as much wilderness as they can. They began assembling land here in Southern Chile in 1991.

Seeing Pumalin From the Sky

Under assault from the massive flies, Doug was eager to show us his Pumalin. The best way to see it: from the air. We clamber into his four-seat Cessna and head for the skies, taking off from the private grass runway next to his ranch.

Doug is an experienced bush pilot, an avid outdoorsman, but that's just the beginning of his resume. He made his millions -- a lot of them -- in the apparel industry in San Francisco, as founder of The North Face, which manufactures adventure and travel gear, and Esprit clothing lines. He abandoned it all 16 years ago to preserve a patch of this planet. A very big patch. Kris Tompkins is also a refugee from the apparel industry: She was CEO of Patagonia Sportswear.

In the air Doug gives his tour over headsets. He explains that there are about 60 miles from the north end of the park to the south end, and between 30 miles and 40 miles from the ocean to the Argentine border.

"We are down here in the middle of Pumalin. You have to understand this is like the size of Yosemite National Park here, so it's pretty big," he said.